feat: Add custom error messages to

Author: pankaj-bind

src/a2a/utils/errors.py

@@ -4,7 +4,7 @@
     ContentTypeNotSupportedError,
     InternalError,
     InvalidAgentResponseError,
-    InvalidParamsError,
+    InvalidParamsError as InvalidParamsErrorType,
     InvalidRequestError,
     JSONParseError,
     JSONRPCError,
@@ -35,6 +35,14 @@ def __init__(
         super().__init__(f'Not Implemented operation Error: {message}')
 
 
+class InvalidParamsError(InvalidParamsErrorType):
+    """
+    JSON-RPC error indicating invalid method parameter(s).
+    """
+
+    message: str = 'Invalid parameters'
+
+
 class ServerError(Exception):
     """Wrapper exception for A2A or JSON-RPC errors originating from the server's logic.
 

tests/utils/test_proto_utils.py

@@ -137,7 +137,23 @@ def test_task_query_params_invalid_name(self):
         request = a2a_pb2.GetTaskRequest(name='invalid-name-format')
         with pytest.raises(ServerError) as exc_info:
             proto_utils.FromProto.task_query_params(request)
+
         assert isinstance(exc_info.value.error, types.InvalidParamsError)
+        assert (
+            exc_info.value.error.message
+            == 'invalid-name-format: invalid-name-format'
+        )
+
+    def test_task_id_params_invalid_name(self):
+        request = a2a_pb2.CancelTaskRequest(name='invalid-name-format')
+        with pytest.raises(ServerError) as exc_info:
+            proto_utils.FromProto.task_id_params(request)
+
+        assert isinstance(exc_info.value.error, types.InvalidParamsError)
+        assert (
+            exc_info.value.error.message
+            == 'invalid-name-format: invalid-name-format'
+        )
 
 
 class TestProtoUtils: